Elemental table question.

[revv]

Well firstly let me say that I am no expert but it seems like the number of protons that determine the different elements is like a puzzle made by the universe? I mean they are all in sequence... am I missing something?

[Sriman Dutta]

In the periodic table, all elements are arranged according to increasing atomic numbers of elements. And atomic number of an element is number of protons present.

[swansont]

Well firstly let me say that I am no expert but it seems like the number of protons that determine the different elements is like a puzzle made by the universe? I mean they are all in sequence... am I missing something?

 

 

They are in sequence because we put them in sequence. The table of the elements is a human-made interpretation of what we observe. Most elements (especially the lighter ones) have stable isotopes, so we have examples of them that are relatively easy to find. But there used to be gaps, when people first started to try and organize their findings. Helium, for example, was discovered relatively late in the game (along with Neon and Argon, two other Noble gases). And Technetium even later, because it has no stable isotopes. Almost all the other later ones are heavier than lead, and all of those are radioactive. Few are naturally occurring.

 

http://www.lenntech.com/periodic-chart-elements/discovery-year.htm

[studiot]

Since you have posted this in Chemistry, I take it this is a Chemistry question.

 

Yes the number of protons determines the actual element concerned - a matter of Physics.

 

But from the Chemist's point of view, the organisation of the 'table' into (horizontal ) octets or periods is much more interesting.

 

This is because the chemical properties are largely determined by the electrons, not the protons and we observe recurring groups of properties.

 

For example the first (vertical) group in the table is known as the alkali metals (Lithium, Sodium, Potassium etc) and the second (vertical) group the alkaline earths.

 

Elements from the same group take aprt in very similar chemical reactions and can often substitute for each other.

 

https://www.google.co.uk/search?hl=en-GB&source=hp&biw=&bih=&q=table+of+elements&gbv=2&oq=table+of+el&gs_l=heirloom-hp.1.0.0l10.1469.4422.0.6328.11.10.0.1.1.0.204.1391.1j7j2.10.0....0...1ac.1.34.heirloom-hp..0.11.1422.86Z3aUlIaKE

Edited November 17, 2016 by studiot

[Sriman Dutta]

Right studiot, the arrangement of the modern periodic table into groups and periods is both interesting as well as significant. Its significance lies in the fact that all elements down a group have same number of valence electrons and the elements across a period have same number of shells. In other words, the group number denotes number of valence electrons and period number represents the number of shells .

[hypervalent_iodine]

Right studiot, the arrangement of the modern periodic table into groups and periods is both interesting as well as significant. Its significance lies in the fact that all elements down a group have same number of valence electrons and the elements across a period have same number of shells. In other words, the group number denotes number of valence electrons and period number represents the number of shells .

 

 

The period number doesn't represent the number of 'shells.'

[kainuri9]

The period number doesn't represent the number of 'shells.'

 

Are you sure? because thats how i learned the table of elements.

[hypervalent_iodine]

Then I'm afraid you learned wrong.

[Sensei]

Are you sure? because thats how i learned the table of elements.

 

How many shells and sub-shells do you have in He, Ne, Ar, Kr, Xe, Rn... ?

[Sriman Dutta]

Wait a minute, I am talking about shells in Bohr's model of the atom, not orbitals in the modern atomic model.

[hypervalent_iodine]

Wait a minute, I am talking about shells in Bohr's model of the atom, not orbitals in the modern atomic model.

Which is still wrong.